This disclosure relates to a method to locate the pudendal nerve, to determine optimum stimulation location and to acutely determine if the patient is responsive to stimulation.
The medical device industry produces a wide variety of electronic and mechanical devices for treating patient medical conditions. Depending upon the medical condition, medical devices can be surgically implanted or connected externally to a patient receiving treatment. Clinicians use medical devices alone or in combination with drug therapies and surgery to treat patient medical conditions. For some medical conditions, medical devices provide the best, and sometimes the only, therapy to restore an individual to a more healthful condition and a fuller life. Conditions that medical devices can effectively treat include pelvic floor disorders.
Pelvic floor disorders adversely affect the health and quality of life of millions of people. Pelvic floor disorders include urinary control disorders such as urge incontinency, urge frequency, voiding efficiency, fecal control disorders, sexual dysfunction, and pelvic pain. Individuals with urinary control disorders often face debilitating challenges in their everyday lives. These individuals can be preoccupied with trips to the bathroom, fears of embarrassment, and sleepless nights. Some suffers become so anxious they become isolated and depressed. Pelvic floor disorders can be treated with a variety of therapeutic options such as behavior modification including biofeedback, pharmacological treatment, mechanical intervention such as self-catheterization, physical appliances such as diapers, and surgical intervention. Surgical treatments are the most invasive and are often considered after other therapies have proven ineffective.
Urinary incontinence, the inability to control the passage of urine, is a relatively common problem. Although there are a variety of different types of urinary incontinence, stress incontinence, urge incontinence and urinary retention are the most common.
Stress incontinence is described by the patient as the unacceptable passage of urine under the stress of increased abdominal pressure. This increased pressure typically results from coughing, sneezing, and Valsalva. Stress incontinence is manifested urologically by normal cystometry, obtuse urethral vesicular angle, abnormally low urethral pressures and a physiologically short urethral length. This disorder is most common in multiparous, post-menopausal females. Physiologically, stress incontinence is a disorder of the volitional muscular control of the urethral resistance to the flow of urine. Laxity and partial denervation of the pelvic musculature is the chief abnormality.
Urge incontinence is described as the involuntary passage of urine with a concomitant sense of urgency. Systometry indicates detrusor (bladder wall muscle) contractions with low bladder filling pressures and volumes. These bladder contractions may not be inhibited in the presence of voluntary EMG signals from the sphincter, indicating reduction or loss of the pudendal-parasympathetic inhibitory reflex. Unsolicited, premature bladder contraction may result from mucosal irritation of varied etiology. These premature contractions of the bladder may also be the result of an abnormally high gain in the detrusor contractile reflex due to the loss of inhibitory control with an upper-motor-neuron lesion.
Urinary retention is characterized by the inability of a patient to spontaneously and controllably urinate or void. Catheterization of the urethra is provided to many patients suffering from urinary retention, which is often a painful and somewhat lengthy procedure having the added risk of causing infection.
Constipation is a life-disturbing problem that afflicts millions of Americans, from the very young to the elderly. Although relatively rare among the young, it is a very common problem in middle age, and is a nearly ubiquitous problem in the elderly.
Chronic constipation is a major problem for many individuals, and frequently causes extreme discomfort to the afflicted. Such discomfort may be a major obstacle to leading a normal life, and may consume an enormous amount of the afflicted person's energy and time.
Besides causing severe discomfort, chronic constipation may also be harmful to the patient. For example, chronic constipation may result in an intestinal obstruction that may cause the patient great pain; or that may even cause the patient's death, unless surgically corrected. Chronic constipation may also prevent the patient from receiving the benefit of certain needed prescription medications, because the medications may have undesirable side effects on an already constipated gut.
Conventional therapies for chronic constipation are often distasteful and unpleasant, at best, since they may involve such treatments as the repeated consumption of large quantities of laxatives such as milk of magnesia, the repetitive use of enemas, or both. Repeatedly consuming large quantities of laxatives may be harmful to the patient, since they may result in dehydration or even renal failure. The repetitive use of enemas may be harmful since they may irritate or physically harm the treated portion of the patient's gut.
Chronic constipation is usually thought of in association with problems of the large intestine. However, other parts of the patient's gut may also exhibit chronic constipation-like problems, such as the esophagus, the stomach, and less frequently, the small intestine. Such problems may include depressed motility of the esophagus, stomach and/or small intestine. For simplicity, chronic constipation, or chronic constipation-like problems, of any portion of the patient's gut from the esophagus to the anus will be referred to hereafter as simply “constipation”.
The prostate is a glandular and fibromuscular organ in the male, which lies immediately below the bladder and surrounds the urethra. Prostatitis, the third leading disease of the prostate, is a common urologic condition that many clinicians find difficult to treat effectively.
The main symptom of chronic prostatitis (category III) is pain, followed by variable voiding (urgency/frequency) and erectile or sexual dysfunction. Patients have symptoms such as painful ejaculation or pain in the penis, testicles, or scrotum; low back, rectal or perineal pain; pain along the inner aspects of the thighs; irritative or obstructive urinary symptoms; and decreased libido or impotence. As a rule, chronic non-bacterial prostatitis patients do not have recurrent urinary tract infections.
Chronic prostatitis is a major male health issue. The average urologist in the U.S. sees 173 prostatitis patients per year, of which one-third are newly diagnosed. The prevalence of prostatitis in the general male population is estimated to be 5-8.8%, and it has been estimated that about 2 million office visits per year are related to prostatitis. Self-reported history of prostatitis is as prevalent as 16%. Patients with chronic prostatitis experience a negative impact on quality of life comparable to patients with unstable angina, recent myocardial infarction, or active Crohn's disease. The average age of the prostatitis population is estimated at 50 years, is the most common urologic diagnosis in men under 50 years old and the third most common in men over 50 years old. The most common classification of prostatitis is chronic prostatitis/chronic pelvic pain syndrome (category III), which may include as many as 90% of all patients who meet the criteria of the condition. Despite the widespread prevalence of prostatitis, the diagnosis of chronic prostatitis represents a particular challenge since its diagnosis is often based on exclusion.
Prostatitis remains poorly understood despite its prevalence because it encompasses multiple diverse disorders that cause symptoms related to the prostate gland. The etiology of acute and chronic bacterial prostatitis is clearly defined, and is a result of pathogenic bacteria that may cause systemic symptoms or urinary tract infections. On the other hand, chronic prostatitis/chronic pelvic pain syndrome does not have a clearly defined etiology, and there are many theories about the cause of this disease.
Perhaps the most encompassing theory of chronic non-bacterial prostatitis involves a multifactorial mechanism initiated by a stimulus such as infection or trauma. An interrelated cascade of events may follow, including physical, chemical, immunologic or neurogenic components, resulting in a local response of inflammation and/or neurogenic injury.
In the absence of consistent or clear etiologies for chronic prostatitis/chronic pelvic pain syndrome, improvement in quality of life and a reduction in symptoms are the usual goals of therapy. The most common treatment of chronic prostatitis includes pharmacologic treatments (antibiotics, anti-inflammatory agents, alpha blockers, anti-spasmodics, analgesics, allopurinol, and muscle relaxants). Alpha blockers have successfully treated symptoms, although adverse event rates have been high. Muscle relaxants have shown significant improvement in small studies for category IIIB patients with sphincter dyssynergia or muscle spasm. Anti-inflammatory agents, such as pentosan polysulfate, have proven successful for approximately 40% of patients with category IIIA prostatitis.
Phytotherapeutic agents have demonstrated improvements in small studies for pain and irritative voiding. Other treatments include physiotherapy (such as biofeedback and pelvic muscle exercises) and various modalities of invasive and minimally invasive procedures (e.g., transurethral microwave therapy, transurethral incision of the bladder neck, hydrodistensions, acupuncture, electroneuromodulation, balloon dilation, YAG laser therapy and heat therapy). Repetitive prostatic massage is a popular treatment method due to the failure of consistent standard medical therapy to treat the condition. Lifestyle changes, such as meditation, discontinuation of bike riding, sitz-baths, dietary changes, and chiropractic therapy, are often utilized.
As a result of unknown etiology, unsure diagnosis, and treatment options that are often myriad and ineffective, chronic prostatitis is a “diagnosis of exclusion” and has a poor record of treatment success. Accordingly, the present invention is intended to provide solutions to the foregoing problems through improved and more effective methods of treating pain and other symptoms associated with chronic prostatitis, prostatalgia and prostatodynia.
Sexual dysfunction comprises a broad range of maladies, including erectile dysfunction, orgasmic dysfunction, premature ejaculation, and lack of lubrication. Sexual dysfunctions plague both women and men, and may be life-long or acquired. To treat impotence (also called erectile dysfunction) it is known to implant electrical conductors to the surface of the pelvic splanchnic nerve. Stimulation of this nerve with low voltage electrical pulses is believed to cause arterioles dilation and initiate erection. Also, it is known that implantation of an electrode on the cavernous nerves of a male, adjacent to his prostate gland, may also achieve penile erection. Further, other electrical impulse devices exist that are not implanted but instead applied topically to the coccyx region to promote sexual excitation. Impotence, however, should not be confused with orgasmic dysfunction where satisfactory erection may be obtained but there is an absence of orgasm.
Current treatment of orgasmic dysfunction concentrates on the psychological components of the disorder rather than the physiological components. Orgasmic dysfunction is a physical malady that results in marked distress and interpersonal difficulty. The physical disorder causes psychological performance anxiety and pressure. Sexual desire and frequency usually decline. The patient's intimate relationships ultimately suffer from resentment and conflict. There is anecdotal evidence of patients who have experienced mild sensation of the genitalia while undergoing spinal cord stimulation for pain relief.
Spinal cord stimulation, on the other hand, has been used as a treatment for chronic painful conditions for approximately thirty years. Commonly, spinal cord stimulation is used to alleviate pain after failed surgery, pain due to neuropathies, or pain due to inadequate blood flow. Neurostimulation systems have been found to relieve chronic, intractable pain in the limbs or trunk.
The basic concept of neurostimulation as it relates to pain relief involves the substitution of sensations that reach the thalamus of the brain. Rather than a pain message, the spinal cord stimulation closes the gate in the spinal cord and replaces the pain sensation with a tingling sensation. Electrodes are positioned effectively to create parathesia in the painful area. Parathesia refers to a change in sensation in an area of the body. Usually parathesia is used to show change in neurologic function caused by damage to a nerve or nerves. Parathesia is usually not an absence of sensation, but a decrease or alteration of sensation. Patients have described parathesia as a “buzzing sensation.”
Parathesia is accomplished through the implantation of stimulating electrodes within the spinal canal. The electrodes are inserted between the vertebrae in parallel with the spinal cord. Low-voltage electrical stimulation is precisely applied to the spinal cord. Through direct stimulation of the dorsal column or the targeted peripheral nerve, the sensation of pain is replaced by a more pleasant “tingling” sensation. The sensation can be adjusted in terms of amplitude to control intensity, pulse width to control duration and frequency. Further, the neurostimulation system is implantable in its entirety. Medtronic Neurological, a division of Medtronic, Inc. of Minneapolis, Minn. sells a neurostimulator system used for pain relief. The device has been approved by the Federal Drug Administration for implantation in the spinal cord to effectively alleviate pain.
One surgical technique to treat urinary control disorders is implantable InterStim® therapy, available from Medtronic, Inc., which applies mild electrical stimulation to the sacral nerves in the lower region of the spine to influence behavior of structures such as the bladder, sphincter and pelvic floor muscles. Generally, implantation of InterStim therapy involves surgically implanting a stimulation lead near the sacral nerves. The stimulation lead is a very small, insulated electrical conductor with electrical stimulation contacts on the distal end placed near the sacral nerves and an electrical connector on the opposite proximal end of the lead. The lead electrical connector is typically connected to a small extension, and the extension is connected to a small neurostimulator that operates similar to a cardiac pacemaker by delivering occasional small electrical pulses that sometimes create a tingling sensation felt by the patient. The stimulation lead, lead extension, and neurostimulator are all implanted in the patient in a manner that is typically not perceptible by others. InterStim therapy can improve the condition of a pelvic floor disorder patient and allow the patient to lead a full life. Also, InterStim therapy is nondestructive and reversible.
Today, stimulation of the sacral nerve is commonly done for the treatment of voiding dysfunction. Although the majority of patients with sacral nerve stimulation obtain satisfactory relief of their voiding dysfunction, some patients do not experience an improvement in symptoms or see annoying side effects that prohibit them from using the therapy.
Electrical stimulation delivered by an intravaginal or a perineal surface electrode has been shown to inhibit premature and inappropriate detrusor contractions. The mechanism for this effect appears to derive from the stimulation of pudendal nerve afferents (sensory receptors or sensory nerve fibers). Input into the pudendal afferent system inhibits a parasympathetic reflex loop consisting of bladder wall afferents (sensory) and efferents (motor). This parasympathetic loop normally senses a distension of the bladder via the afferent limb and responds by sending an efferent signal to contract the bladder. Although this stimulation has shown therapeutic effects, electrode placement and on-going stimulation does not lend itself toward chronic stimulation.
Stimulation of the pudendal nerve as an alternative to sacral nerve stimulation has been proposed previously. The invasiveness of surgical procedures made stimulation of the pudendal nerve impractical, however.
Some prior art publications relating to various embodiments of the present invention are listed in Table 1 below.
Table 1: Prior Art Publications
Juenemann et al., “Clinical Significance of Sacral and Pudendal Nerve Anatomy,”The Journal of Urology, Vol. 139, pp. 74-80 (January, 1988).
Schmidt, Richard A., “Technique of Pudendal Nerve Localization for Block or Stimulation,” The Journal of Urology, Vol. 142(December, 1989).
U.S. Pat. No. 4,406,288 to Cash for “Bladder Control Device and Method”
U.S. Pat. No. 4,607,639 to Tanagho et al. for “Method and System for Controlling Bladder Evacuation.”
U.S. Pat. No. 4,771,779 to Tanagho et al. for “System for Controlling Bladder Evacuation.”
U.S. Pat. No. 4,739,764 to Lue et al. for “Method for Stimulating Pelvic Floor Muscles for Regulating Pelvic Viscera.”
U.S. Pat. No. 4,881,526 to Johnson et al. for “Intravaginal Electrode and Stimulation System for Controlling Female Urinary Incontinence”
U.S. Pat. No. 5,425,751 to Baeten et al. for “Method and Apparatus for Optimum Positioning of a Muscle Stimulating Implant”
U.S. Pat. No. 5,984,854 to Ishikawa et al. for “Method for Treating Urinary Incontinence and Apparatus Therefor”
U.S. Pat. No. 6,055,456 to Gerber for “Single and Multi-Polar Implantable Lead for Sacral Nerve Stimulation”
U.S. Pat. No. 6,366,814 to Boveja. for “Electrical Stimulation Adjunct (Add-On) Therapy for Urinary Incontinence and Urological Disorders Using an External Stimulator”
U.S. Pat. No. 6,449,512 to Boveja. for “Apparatus and Method for Treatment of Urological Disorders Using Programmerless Implantable Pulse Generator System”
U.S. patent application Publication No. 2002/0055761 to Mann et al. for “Implantable Stimulator Systems and Methods for Treatment of Incontinence and Pain”
U.S. patent application Publication No. 2002/0055779 to Andrews for “Neural Prosthesis”
PCT Patent Application WO 02/078592 to Grill et al. for “Systems and Methods for Selectively Stimulating Components In, On or Near the Pudendal Nerve or Its Branches to Achieve Selective Physiologic Responses”
European Patent Application No. 0 245 547 to Tanagho et al. for “Electronic Control System for Controlling Pelvic Viscera via Neuro-Electrical Stimulation.”
All patents and technical papers listed in Table 1 hereinabove are hereby incorporated by reference herein, each in its respective entirety. As those of ordinary skill in the art will appreciate readily upon reading the Summary of the Invention, Detailed Description of the Preferred Embodiments and Claims set forth below, at least some of the devices and methods disclosed in the patents and publications of Table 1 may be modified advantageously in accordance with the teachings of the present invention. The foregoing and other objects, features and advantages, which will now become more readily apparent by referring to the following specification, drawings and claims, are provided by the various embodiments of the present invention.
For the foregoing reasons, there exists an unfulfilled need in the art for a method to locate the pudendal nerve, to determine optimum electrical stimulation locations and to determine acutely whether a patient respond to electrical stimulation therapy.